In a typical mobile communications environment, a user equipment (UE) communicates voice and/or data signals with one or more service networks via base stations (also referred to as “eNBs”). The wireless communications between the UE and the service networks complies with various wireless communication standards, such as the Global System for Mobile communications (GSM) technology, Wideband Code Division Multiple Access (WCDMA) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Long Term Evolution (LTE) technology, etc.
Recently, techniques empowering full mechanical automation (e.g., the Internet of Things) are emerging. Some of these techniques require wireless communications between machine-type communications (MTC) devices. Such communications are also known as machine-to-machine (M2M) communications. MTC communication has some unique features different from the human-to-human (H2H) communications. For example, an MTC device like a smart utility meter typically generates a small data transmission during a predefined reporting interval and then goes to sleep for a long time period until the next reporting interval. In another example, a MTC device may only transmit a short but important alarm message. Therefore, the reliability of the MTC communication is important.